Without sperm or egg, how scientists grew whole model of human embryo

Source: The post is based on the article “Without sperm or egg, how scientists grew whole model of human embryo” published in Indian Express on 8th September 2023

What is the News?

Scientists have successfully grown a “human embryo” in the lab without using an egg or sperm.

How did scientists grow a human embryo in the lab without using an egg or sperm?

Source: BBC

Instead of a sperm and egg, the starting material was stem cells which were reprogrammed to gain the potential to become any type of tissue in the body.

Chemicals were then used to coax these stem cells into becoming four types of cell found in the earliest stages of the human embryo: 1) epiblast cells, which become the embryo proper (or foetus) 2) trophoblast cells, which become the placenta 3) hypoblast cells, which become the supportive yolk sac and 4) extraembryonic mesoderm cells.

A total of 120 of these stem cells were mixed in a precise ratio – and then, the scientists step back and watch.

About 1% of the mixture began the journey of spontaneously assembling themselves into a structure that resembles a human embryo.

The embryo models were allowed to grow and develop until they were comparable to an embryo 14 days after fertilization.In many countries, this is the legal cut-off for normal embryo research.

Why are embryo models and research important?

There is no way for scientists to ethically research the early stages of development of an embryo, as it is difficult to study it after it implants in the uterus.Scientists currently study these initial changes in various lab models or donated embryos.

This research is crucial because the initial days of embryo development is when the majority of miscarriages and birth defects occur.Studying these initial stages may help scientists understand genetic and inherited diseases better.

Moreover, the understanding of why some embryos develop normally, retain the proper genetic code and implant properly in the womb while others do not may also help in improving success rates of in vitro fertilization.

Can lab-grown embryos be used to get pregnant?

No.These models are meant to just study the early stages of development of a foetus.

It is generally accepted — and legally supported in most countries — that these embryo models will be destroyed after studying the first 14 days. Attempts to implant are not allowed.

Why is there a 14-day limit on embryo research?

The limit was first proposed by a committee in the UK in 1979 after the birth of the first test tube baby Louise Brown demonstrated that embryos could be kept alive in laboratories. 

The 14-day period is equivalent to when embryos naturally finish implantation. It is also when cells start becoming an “individual”, and breaking off into a twin is not possible.